It would seem to be the places with the titan production facilities would be the final two, so Pandaria vs Northrend. That would be an interesting fight. If the dragons instead alligned as the Wyrmrest, and were Northrend, that combined with whatever the Scourge could rez, but then again the Mantid has a swarm. fun!

All this does is make me want to see a RISK game including all four continents! Are there some already?

Northrend gets my vote. We can all agree that whatever else happens, there will be massive casualties. Even if the vast swarms of the mantid and hordes of mogu destroy EK and Kalimdor with minimal effort they will soon find themselves fighting everything they just killed a second time - but now all working together and with the armies of northrend to back them up. Also note that in the wrathgate cinematic the lich king was shown to be capable of re-resurrecting the forces killed by the initial alliance/horde attack, showing that (even if its a lich king specific power) the armies of pandaria would potentially be forced to fight waves of undead that just got back up as soon as they fell.

While mogu constructs would surely not tire, weight of numbers will wipe them out. Mantid may have HUGE numbers themselves (not sure how large their population is supposed to be at the current point in timeline) but the fate of the nerubians shows that being raised is not a humanoid only fate - their armies would simply be overwhelmed.

Note - I have not even mentioned any force in Northrend apart from the scourge. Dalaran/iron dwarves/earthen/titanic constructs etc would not even be needed to win this war. I have also not discussed the forces of EK and Kalimdor vs Northrend because it has been clearly stated in lore that if the scourge is unleashed, they will both fall.

When one side can raise the countless dead to fight for them, there can only be one winner.

The side with more undead on it would win, and seeing as Sylvanas probably doesn't come any close to LK's (or rather, the warden's of the damned, hurr durr) power, that's Northrend. The only way to beat the Scourge at full power is by using weapons of mass destruction (which gnomes probably have, so that's something going for EK) or having armies immune to undeath (be it mechanical, elemental or immune by other means, like worgen).

So, actually, EK may have a chance against Northrend, the others - not so much.

Yes on 2 Still Kalimdor, they have The two oldest playable race in WoW (NE/Troll), plus the 2 biggest races (Cow/Space Cow), a smart but destrutive race (goblin), and the Orc (don't know where to put them)

(note: Northern would be the weakest because they don't have a playable race)

Pandaria was saved from the sha and mantid and mogu by a small task force from each faction. the minute the huge war machine of each faction arrives on the coast its pretty much domination. Pandaria is probally the least powerful

Easy win here by the scourge, bolivar needed to sacrifice himself inorder to keep them in check and raging across the lands.But if brought to war, the armies of the scourge would easily over eastern and kalimdor with ease. (and pandaria). The things we should take away from wotlk ending is that, with bolivar, the other the horde and the alliance believe the lich king is dead, and his army decimated, so a mass scourge sneak attack on all fronts would easily massacre them. And the dead would rise to new soldiers. And they dont need to be deviated from their goal of killing and rising to go summon demonlords this time.